
/* @(#)w_cosh.c 5.1 93/09/24 */
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

/*

FUNCTION
        <<cosh>>, <<coshf>>---hyperbolic cosine

ANSI_SYNOPSIS
        #include <math.h>
        double cosh(double <[x]>);
        float coshf(float <[x]>)

TRAD_SYNOPSIS
        #include <math.h>
        double cosh(<[x]>)
        double <[x]>;

        float coshf(<[x]>)
        float <[x]>;

DESCRIPTION

    <<cosh>> computes the hyperbolic cosine of the argument <[x]>.
    <<cosh(<[x]>)>> is defined as
    @ifnottex
    . (exp(x) + exp(-x))/2
    @end ifnottex
    @tex
    $${(e^x + e^{-x})} \over 2$$
    @end tex

    Angles are specified in radians.

    <<coshf>> is identical, save that it takes and returns <<float>>.

RETURNS
    The computed value is returned.  When the correct value would create
    an overflow,  <<cosh>> returns the value <<HUGE_VAL>> with the
    appropriate sign, and the global value <<errno>> is set to <<ERANGE>>.

    You can modify error handling for these functions using the
    function <<matherr>>.

PORTABILITY
    <<cosh>> is ANSI.
    <<coshf>> is an extension.

QUICKREF
    cosh ansi pure
    coshf - pure
*/

/*
 * wrapper cosh(x)
 */

#include "fdlibm.h"
#include <errno.h>

#ifndef _DOUBLE_IS_32BITS

#ifdef __STDC__
    double cosh(double x)       /* wrapper cosh */
#else
    double cosh(x)          /* wrapper cosh */
    double x;
#endif
{
#ifdef _IEEE_LIBM
    return __ieee754_cosh(x);
#else
    double z;
    struct exception exc;
    z = __ieee754_cosh(x);
    if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
    if(fabs(x)>7.10475860073943863426e+02) {
        /* cosh(finite) overflow */
#ifndef HUGE_VAL
#define HUGE_VAL inf
        double inf = 0.0;

        SET_HIGH_WORD(inf,0x7ff00000);  /* set inf to infinite */
#endif
        exc.type = OVERFLOW;
        exc.name = "cosh";
        exc.err = 0;
        exc.arg1 = exc.arg2 = x;
        if (_LIB_VERSION == _SVID_)
           exc.retval = HUGE;
        else
           exc.retval = HUGE_VAL;
        if (_LIB_VERSION == _POSIX_)
           Djy_SaveLastError(ERANGE);
        else if (!matherr(&exc)) {
           Djy_SaveLastError(ERANGE);
        }
        if (exc.err != 0)
           Djy_SaveLastError(exc.err);
        return exc.retval;
    } else
        return z;
#endif
}

#endif /* defined(_DOUBLE_IS_32BITS) */
